This invention relates to paper and its production. More specifically, this invention relates to a nonlaminated paper of variable basis weight. In a preferred embodiment of the present invention, the paper described herein possesses regions of increased basis weight. These regions of increased basis weight are crossdirectional, i.e., they are oriented substantially parallel to the crossdirection of the paper and orthogonal to the machine direction of the paper. As used herein, basis weight is meant the weight of the paper per unit surface area, and is expressed in grams per square meter.
Paper such as that described herein is particularly useful as a wrapping material for smoking articles, although other uses are within the scope of this invention. For example, the paper of this invention has applications in banking, industrial, and household uses.
In the papermaking art, it is often customary to produce paper whose basis weight is as uniform as possible. Sheets of paper produced during standard papermaking processes are, therefore, usually of uniform basis weight when the paper is considered as a whole. Microscopic variations in the basis weight of the paper do nonetheless occur because of variations in the size of the constituent fibers or fluctuations in the manufacturing process.
Paper used in the tobacco industry as cigarette wrapping material has commonly been of uniform basis weight to promote even burn characteristics in the smoking article. It is now desirable to produce a cigarette wrapping paper which imparts special burn characteristics, e.g., the paper promotes a decrease in the static burn rate of the smoking article to the point that combustion of the article is decreased, substantially negligible, or terminates altogether. Such a wrapping paper, as described herein, possesses a plurality of crossdirectional regions of increased basis weight.
There have been attempts to produce nonlaminated paper of increased thickness. For example, Blake U.S. Pat. No. 4,239,591 refers to the production of paper having either islands or continuous regions of increased thickness. One drawback of this invention is that the regions of increased thickness run in the direction that the web is laid down.
There have been attempts to produce wrappers for smoking articles designed to reduce the Burn Mode Index in a laminated portion thereof. For example, Hampl U.S. Pat. No. 4,739,775 refers to wrappers which have bands laminated to cigarette paper.
Mentzel et al. U.S. Pat. No. 4,945,932 refers to a cigarette of reduced combustion proclivity having batonned paper.
There have been attempts to decrease the burn rate of wrapping materials for smoking articles. These attempts involve incorporating into the wrapping material a burn retardant such as magnesium acetate. These burn retardants can contribute undesirable flavors to the smoking article upon combustion.
It would be desirable to provide a nonlaminated paper having a plurality of crossdirectional regions of increased basis weight.
It would further be desirable to provide a paper which is useful as a wrapping material that alters the puff count of a smoking article.
It would be desirable to reduce the amounts of burn retardants used in wrapping materials for a smoking article.
It would also be desirable to provide paper useful as a wrapping material for a smoking article which permits increased use of expanded tobacco.
It would be further desirable to provide a method for producing non-laminated paper having regions of variable basis weight in the crossdirection.
It would also be desirable to provide a method for producing paper which allows a wide variety of materials to be laid down in the crossdirection of the paper.